1. Field of the Invention
The present invention relates to a bulldozer which is provided with a blade which is a work machine and a blade control method for the bulldozer.
2. Background Information
A bulldozer which is one example of a work vehicle is a tractor which has a crawler movement apparatus and is provided with an earth moving plate (blade) as a work machine at the front of the vehicle. The blade is used for work such as bulldozing work where surface earth or the like is pushed and carried and ground leveling work where the ground surface is flattened.
In the past, a method has been proposed for automatically lowering the blade to where the lower edge of the blade comes into contact with the ground surface according to switching of transmission during bulldozing work in automatic driving to an advancing state (refer to U.S. Pat. No. 5,555,942). According to this method, it is possible to assist an operator such that it is possible to easily start bulldozing work where it is necessary to repeat forward and backward movement.
Here, a digging mode and ground leveling mode are generally included in the bulldozing work in automatic driving. The digging mode is a mode in which the height of the blade is automatically adjusted with regard to the designed surface such that a load which is applied on the blade enters a predetermined range while the blade is observed so as not to be lowered below the designed surface. The ground leveling mode is a mode in which the height of the blade is automatically adjusted with regard to the designed surface such that a cutting edge of the blade is moved along the designed surface.